CHANGES IN SHAPE ASSOCIATED WITH GROWTH IN THE LOLIGINID SQUID PHOTOLOLIGO SP - A MORPHOMETRIC APPROACH

This study examined growth of squid by describing changes in shape and relative size of body structures in juvenile and adult Photololigo sp . Animals change shape during growth because body structures increase in size at different relative rates. These changes are of particular i nterest because they are generally concomitant with changes in ecology . Length and mass measurements were taken from Photololigo sp. ranging in size from 2.77 to 117.03 mm dorsal mantle length. Small squid (<50 mm dorsal mantle length) had round bodies with large head and eyes an d poorly developed tentacles and arms. Larger squid (>50 mm dorsal man tle length) were more elongate and narrow, and the head and eyes were proportionally smaller. As squid reached a dorsal mantle length of 50 mm, the changes in shape with growth become slower and individuals rea ched a final shape. Small individuals allocated energy predominantly i n the arms and tentacles during early stages of growth, while the visc era and head grew at a much slower rate. Once individuals began produc ing gametic tissue and gonad growth occurred, the mantle muscle grew m ore slowly than the gonad. Changes in shape could be related to change s in locomotion and feeding that occur during ontogeny.